Substrate processing apparatus, program for performing operation and control method thereof, and computer readable storage medium storing the program

ABSTRACT

A computer readable storage medium storing a program for performing an operation method of a substrate processing apparatus is provided. The operation method includes the steps of introducing a nonreactive gas into the vacuum preparation chamber before the gate valve is opened while the substrate is transferred between the vacuum preparation chamber of the vacuum processing unit and the transfer unit, stopping introducing the nonreactive gas when an inner pressure of the vacuum preparation chamber becomes same as an atmospheric pressure, starting an evacuation process of the corrosive gas in the vacuum preparation chamber and then opening to atmosphere performed by letting the vacuum preparation chamber communicate with an atmosphere, and opening the gate valve after the step of opening to atmosphere.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/254,668, filed Oct. 21, 2005, which claims priority to JapanesePatent Application No. 2004-313475, filed Oct. 28, 2004 and U.S.Provisional Application No. 60/635,945, filed Dec. 15, 2004. The entirecontents of these applications are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to a substrate processing apparatus, aprogram for performing operation and control method thereof, and acomputer readable storage medium for storing the program.

BACKGROUND OF THE INVENTION

A substrate processing apparatus includes a plurality of chambersconnected with each other. Among those chambers, there are a transferchamber, provided in a transfer unit, for transferring a substrate to beprocessed, e.g., a semiconductor wafer (hereinafter, simply referred toas a “wafer”), between the transfer chamber under the atmosphericpressure and the outside; a vacuum processing chamber for performing aspecified process such as etching or film forming process on the wafer;and a vacuum preparation chamber (e.g., load-lock chamber) which isdisposed between the vacuum processing chamber and the transfer chamberto be connected with them. The chambers are sealed and connected to eachother via gate valves.

In the substrate processing apparatus, the wafer is transferred betweenthose chambers and processed in the vacuum processing chamber.Generally, the wafer is transferred in the substrate processingapparatus including those chambers as follows. For example, the wafer isloaded into the transfer chamber from the outside. Further, the wafer isthen loaded into the vacuum processing chamber through the vacuumpreparation chamber. Then, a processing such as etching or film formingprocess is carried out on the wafer in the vacuum processing chamber byusing a specified processing gas. When the processing is finished in thevacuum processing chamber, the wafer is transferred back to the transferchamber via the vacuum preparation chamber. In a wafer transfer betweenthe vacuum preparation chamber and the transfer chamber, once thepressure in the vacuum preparation chamber reaches a specified pressure,for example, by opening the chamber to the atmosphere, the gate valvebetween the chambers is opened and the wafer is transferred between thevacuum preparation chamber and the transfer chamber. Further, in a wafertransfer between the vacuum preparation chamber and the vacuum chamber,once the vacuum preparation chamber reaches to a predetermined pressure,for example, by vacuum processing, the gate valve between the chambersis opened and the wafer is transferred between the vacuum preparationchamber and the vacuum processing chamber. In other words, when thewafer is transferred between the chambers, each chamber is controlled toset its pressure at a specified value in order to reduce a pressuredifference between the chambers.

However, depending on a pressure condition of each chamber, when thegate valve is opened between the chambers, there give rise to variousproblems such as a processing gas remaining in the vacuum processingchamber flowing backward; contaminant such as water being introducedfrom the transfer chamber; and particles (deposits, dust and the like)being swirled up in the chambers. Accordingly, the wafer may becontaminated by the particles or contaminant. Further, when a corrosiveprocessing gas flows backward into another chamber, the components inthe chamber may be corroded.

Thus, conventionally, before the gate valve is opened, a pressure in thechamber is controlled in many ways. For example, in case that the vacuumpreparation chamber is opened to the atmosphere when the gate valvebetween the transfer chamber and the vacuum preparation chamber isopened, the vacuum preparation chamber is evacuated while supplying apurge gas such as N₂ gas thereto for the purpose of removing theparticles present in the vacuum preparation chamber in advance (see,e.g., Japanese Patent Laid-open Publication No. H3-087386).

Further, in a so-called cluster tool type substrate processingapparatus, wherein a plurality of vacuum processing chambers areconnected to a common transfer chamber and a vacuum preparation chamber(load-lock chamber) is connected to the common transfer chamber, when agate valve between the common transfer chamber and one of the vacuumprocessing chambers or between the common transfer chamber and theload-lock chamber is opened, a pressure of the common transfer chamberis made slightly higher than that of the vacuum processing chamber orthe load-lock chamber by supplying a purge gas such as N₂ gas to thecommon transfer chamber, thereby forming a gas flow from the commontransfer chamber to the vacuum processing chamber or the load-lockchamber. Accordingly, a processing gas or contaminant such as water isprevented from flowing into the common transfer chamber (see, e.g.,Japanese Patent Laid-open Publication No. H7-211761)

However, in the aforementioned conventional technology, in order toprevent the backflow of the processing gas and cross contamination andto remove the particles, the pressure of the relevant chamber iscontrolled by supplying the purge gas such as N₂ gas to thereby cause apressure difference between the chambers.

Depending on the pressure difference between the chambers, a gas flow isgenerated when the gate valve is opened, and particles are swirled upalong the flow in the chamber. Particularly, when the pressuredifference between the chambers is large, a shock wave (very strongpressure wave which is transmitted at a supersonic speed whencompressible fluid flows at a high speed) is generated and along thepropagation of the shock wave, the particles will be swirled up in thechamber.

Thus, by slightly reducing the pressure difference between the chambers,one may expect to prevent the swirling up of particles. But, recently,airtightness of the chambers is further enhanced due to improvement insealing technology. Accordingly, in the conventional sequence ofpressure control, the inner pressure of the chamber becomes needlesslyhigh due to, e.g., the introduction of the purge gas, thereby needlesslyincreasing an actual pressure difference between chambers.

Further, it may be possible to accurately control the pressure of eachchamber such that the pressure difference between chambers does notbecome excessively high by precisely measuring the pressures of allchambers. However, in order to accurately control the pressure, anexpensive pressure gauge or a control apparatus is required to therebyincrease the cost and, further, it is not practical because the sequenceof the pressure control becomes too complicated.

Further, Japanese Patent Laid-open Publication No. H7-211761 disclosesthat a bypass capable of being opened or closed is provided between thechambers and the bypass is opened before the gate valve is opened toreduce the pressure difference between the chambers, whereby forming arapid flow of gas (pressure wave) is prevented when the gate valve isopened. However, when the bypass is opened, depending on the pressuredifference between the chambers, a shock wave may be generated evenbefore the gate valve is opened and propagate into the chamber, therebymaking particles be swirled up.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide asubstrate processing apparatus, a program for performing operation andcontrol method thereof, and a computer readable storage medium forstoring the program capable of effectively preventing particles frombeing swirled up in a chamber by suppressing a shock wave or convectioncaused when the gate valve is opened between chambers by means of asimple configuration.

To achieve the object, in accordance with an aspect of the presentinvention, there is provided a computer readable storage medium storinga program for performing an operation method of a substrate processingapparatus which includes a transfer unit for transferring a substrate tobe processed between a transfer chamber and the outside; and at leastone vacuum processing unit, connected to the transfer unit, having avacuum preparation chamber connected to the transfer unit via a gatevalve and at least one vacuum processing chamber for performing aprocess on the substrate loaded therein via the vacuum preparationchamber by using a corrosive gas as a processing gas, the methodincluding the steps of introducing a nonreactive gas into the vacuumpreparation chamber before the gate valve is opened while the substrateis transferred between the vacuum preparation chamber of the vacuumprocessing unit and the transfer unit; stopping introducing thenonreactive gas when an inner pressure of the vacuum preparation chamberbecomes same as an atmospheric pressure, starting an evacuation processof the corrosive gas in the vacuum preparation chamber and then openingto atmosphere performed by letting the vacuum preparation chambercommunicate with an atmosphere; and opening the gate valve after thestep of opening to atmosphere.

To achieve the object, in accordance with another aspect of the presentinvention, there is provided a computer readable storage medium storinga program for performing a control method of a substrate processingapparatus which includes a transfer unit for transferring a substrate tobe processed between a transfer chamber and the outside; and at leastone vacuum processing unit, connected to the transfer unit, having avacuum preparation chamber connected to the transfer unit via a gatevalve and at least one vacuum processing chamber for performing aprocess on the substrate loaded therein via the vacuum preparationchamber by using a corrosive gas as a processing gas, wherein the vacuumpreparation chamber has a nonreactive gas introducing unit, a corrosivegas evacuation unit, an opening-to-atmosphere unit and the like, themethod including the steps of introducing a nonreactive gas into thevacuum preparation chamber by controlling a gas introduction valve ofthe nonreactive gas introducing unit before the gate valve is openedwhile the substrate is transferred between the vacuum preparationchamber of the vacuum processing unit and the transfer unit; stoppingintroducing the nonreactive gas by controlling the gas introductionvalve of the nonreactive gas introducing unit when an atmosphericpressure state detecting unit provided in the vacuum preparation chamberdetermines that an inner pressure of the vacuum preparation chamberbecomes same as an atmospheric pressure, starting an evacuation processof the corrosive gas in the vacuum preparation chamber by controlling anevacuation valve of the corrosive gas evacuation unit and then openingto atmosphere performed by letting the vacuum preparation chambercommunicate with an atmosphere by controlling an opening-to-atmospherevalve of the opening-to-atmosphere unit; and opening the gate valve bycontrolling it after the step of opening to atmosphere.

To achieve the object, in accordance with still another aspect of thepresent invention, there is provided a substrate processing apparatusincluding a transfer unit for transferring a substrate to be processedbetween a transfer chamber and the outside; at least one vacuumprocessing unit connected to the transfer unit; at least one vacuumpreparation chamber provided in the vacuum processing unit and connectedto the transfer unit via a gate valve, having a nonreactive gasintroducing unit, a corrosive gas evacuation unit, anopening-to-atmosphere unit and the like; at least one vacuum processingchamber, provided in the vacuum processing unit, for performing aprocess on the substrate loaded therein via the vacuum preparationchamber by using a corrosive gas as a processing gas; and a controllerfor introducing a nonreactive gas into the vacuum preparation chamber bycontrolling a gas introduction valve of the nonreactive gas introducingunit before the gate valve is opened while the substrate is transferredbetween the vacuum preparation chamber of the vacuum processing unit andthe transfer unit; stopping introducing the nonreactive gas bycontrolling the gas introduction valve of the nonreactive gasintroducing unit when it is determined that an inner pressure of thevacuum preparation chamber becomes same as an atmospheric pressure,starting an evacuation process of the corrosive gas in the vacuumpreparation chamber by controlling an evacuation valve of the corrosivegas evacuation unit and then opening to atmosphere performed by lettingthe vacuum preparation chamber communicate with an atmosphere bycontrolling an opening-to-atmosphere valve of the opening-to-atmosphereunit; and opening the gate valve by controlling it after the step ofopening to atmosphere.

To achieve the object, in accordance with still another aspect of thepresent invention, there is provided a program for performing a controlmethod of a substrate processing apparatus which includes a transferunit for transferring a substrate to be processed between a transferchamber and the outside; and at least one vacuum processing unit,connected to the transfer unit, having a vacuum preparation chamberconnected to the transfer unit via a gate valve and at least one vacuumprocessing chamber for performing a process on the substrate loadedtherein via the vacuum preparation chamber by using a corrosive gas as aprocessing gas, wherein the vacuum preparation chamber has a nonreactivegas introducing unit, a corrosive gas evacuation unit, anopening-to-atmosphere unit and the like, the method including the stepsof opening a gas introduction valve of the nonreactive gas introducingunit before the gate valve is opened when the substrate is transferredbetween the vacuum preparation chamber of the vacuum processing unit andthe transfer unit; closing the gas introduction valve of the nonreactivegas introducing unit when an atmospheric pressure state detecting unitprovided in the vacuum preparation chamber determines that an innerpressure of the vacuum preparation chamber becomes same as anatmospheric pressure, simultaneously opening an evacuation valve of thecorrosive gas evacuation unit and then opening to atmosphere performedby opening an opening-to-atmosphere valve of the opening-to-atmosphereunit; and opening the gate valve.

In accordance with the computer readable storage medium, the apparatusand the program of the present invention, even though a nonreactive gasis introduced into the vacuum preparation chamber, the introduction ofthe nonreactive gas can be stopped at an early stage, thereby preventingthe pressure of the vacuum preparation chamber from becoming needlesslyincreased. Further, an evacuation of corrosive gas in the vacuumpreparation chamber can be started at an early stage, whereby corrosivegas and the like remaining in the vacuum preparation chamber can beevacuated in advance before the gate valve is opened. Accordingly,although the opening-to-atmosphere valve is opened after that, thecorrosive gas can be prevented from flowing into, e.g., the transferchamber. Resultantly, it can be also prevented that, for example, partsof mechanisms in the transfer chamber are corroded. As described above,in accordance with the present invention, by simply configuring that theintroduction of the nonreactive gas is stopped and, at the same time,the evacuation of the corrosive gas in the vacuum preparation chamber isstarted at an early stage, it can be prevented that the pressure of thevacuum preparation chamber becomes needlessly increased. Consequently, ashock wave or rapid convection can be prevented from occurring when thegate valve between the chambers is opened, thereby effectivelypreventing particles from being swirled up in the chamber.

Further, in the computer readable storage medium, timings of stoppingintroducing the nonreactive gas and starting the evacuation process ofthe corrosive gas can be freely set in the step of opening to atmosphereand, for example, they may be same as a timing when the inner pressureof the vacuum preparation chamber becomes same as the atmosphericpressure. Accordingly, by controlling timings of stopping introducingthe nonreactive gas and starting the evacuation process of the corrosivegas, particles can be prevented from being swirled up due to a pressuredifference between the vacuum preparation chamber and the transfer unitwhen the gate valve is opened. In accordance with the present invention,by simply configuring that timings of stopping introducing thenonreactive gas and starting the evacuation process of the corrosive gasare adjusted, it can be prevented that the pressure of the vacuumpreparation chamber becomes needlessly increased. Consequently, a shockwave or rapid convection can be prevented from occurring when the gatevalve between the chambers (in this case, between the vacuum preparationchamber and the transfer unit) is opened, thereby effectively preventingparticles from being swirled up in the chamber.

Further, in the computer readable storage medium, the substrateprocessing apparatus further includes a backflow detecting unit fordetecting a backflow in the evacuation process of the corrosive gas, andwhen the backflow is detected during the evacuation process by thebackflow detecting unit after starting the evacuation process of thecorrosive gas in the vacuum preparation chamber, preferably, an errorprocess is performed if the backflow is not controlled within aspecified time period and the error process is not performed if thebackflow is controlled within a specified time period. Accordingly,although the backflow is detected momentarily, the error process is notconducted if the backflow becomes controlled within the specified timeperiod. Thus, even though the evacuation valve is opened early beforethe gate valve is opened as in the present invention and the errorprocess is closing the evacuation valve, for example, when the backflowoccurs, it is possible to avoid a problem such as the one that theevacuation valve is closed just simply because a momentary backflow hasoccurred.

Further, in the substrate processing apparatus, a shock wave preventingmechanism for preventing a shock wave occurring depending on a pressuredifference between the vacuum preparation chamber and the transfer unitmay be provided therebetween. In addition, a shock wave preventingmechanism for preventing a shock wave occurring depending on a pressuredifference between the vacuum preparation chamber and the vacuumprocessing chamber may be provided therebetween. The shock wavepreventing mechanism includes a communication pipe for letting thevacuum preparation chamber communicate with the transfer unit or thevacuum processing chamber; a shock wave propagation preventing unitdisposed in the communication pipe; and a communication pipeopening/closing valve disposed at one side of the shock wave propagationpreventing unit, close to the vacuum preparation chamber having a higherpressure.

In the substrate processing apparatus provided with the shock wavepreventing mechanism, the gate valve can be opened after, e.g., thecommunication pipe opening/closing valve is opened. Accordingly, even ifthere is the pressure difference between the vacuum preparation chamberand the transfer unit (or the vacuum processing chamber), the shock waveoccurring when opening the communication pipe opening/closing valveremains in the communication pipe by the presence of the shock wavepropagation preventing unit without propagating, thereby preventing theswirling up of particles is caused by a shock wave. Further, because thepressure difference between the vacuum preparation chamber and thetransfer unit (or the vacuum processing chamber) is reduced by openingthe communication pipe opening/closing valve, even though the gate valveis opened after that, a shock wave does not occur to thereby prevent theparticles from being swirled up along the shock wave.

To achieve the object, in accordance with still another aspect of thepresent invention, there is provided a substrate processing apparatusincluding a plurality of chambers at least including a vacuum processingchamber for performing a process on a substrate to be processed by usinga processing gas, wherein the substrate is transferred between thechambers; and a shock wave preventing mechanism for preventing a shockwave occurring depending on a pressure difference between chambershaving at least a pressure difference among the plurality of chambers.

Further, the shock wave preventing mechanism includes a communicationpipe for letting the chambers communicate with each other; a shock wavepropagation preventing unit disposed in the communication pipe; and acommunication pipe opening/closing valve disposed at one side of theshock wave propagation preventing unit, close to the vacuum preparationchamber having a higher pressure. Additionally, when the processing gasis a corrosive gas, the communication pipe may be provided with acommunication pipe opening/closing valve also disposed at another sideof the shock wave propagation preventing unit, close to the vacuumpreparation chamber having a lower pressure, and a vacuum evacuationunit for vacuum processing the communication pipe, which is providedbetween the shock wave propagation preventing unit and the communicationpipe opening/closing valve disposed at said another side of the shockwave propagation preventing unit.

To achieve the object, in accordance with still another aspect of thepresent invention, there is provided a computer readable storage mediumstoring a program for performing a control method of a substrateprocessing apparatus which includes a plurality of chambers at leastincluding a vacuum processing chamber for performing a process on asubstrate to be processed by using a processing gas, wherein thesubstrate is transferred between the chambers via a gate valve; and ashock wave preventing mechanism having a communication pipe for lettingthe chambers communicate with each other, a shock wave propagationpreventing unit disposed in the communication pipe, and a communicationpipe opening/closing valve disposed at one side of the shock wavepropagation preventing unit, close to the vacuum preparation chamberhaving a higher pressure, wherein the gate valve is opened after openingthe communication pipe opening/closing valve to make the chamberscommunicate with each other via the communication pipe.

In the substrate processing apparatus provided with the shock wavepreventing mechanism, the gate valve is opened after, e.g., thecommunication pipe opening/closing valve is opened. Accordingly, even ifthere is the pressure difference between the chambers, the shock waveoccurring when opening the communication pipe opening/closing valveremains in the communication pipe by the presence of the shock wavepropagation preventing unit without propagating. Further, because thepressure difference between the chambers is reduced by opening thecommunication pipe opening/closing valve, even though the gate valve isopened after that, a shock wave does not occur. In accordance with thepresent invention, by simply configuring that the communication pipe isdisposed between the chambers and, simultaneously, the shock wavepropagation preventing unit is provided in the communication pipe, ashock wave or rapid convection can be prevented from occurring when thegate valve between the chambers is opened, thereby effectivelypreventing particles from being swirled up in the chamber.

To achieve the object, in accordance with still another aspect of thepresent invention, there is provided a computer readable storage mediumstoring a program for performing a control method of a substrateprocessing apparatus which includes a plurality of chambers at leastincluding a vacuum processing chamber for performing a process on asubstrate to be processed by using a processing gas, wherein thesubstrate is transferred between the chambers via a gate valve; and ashock wave preventing mechanism having a communication pipe for makingthe chambers communicate with each other, a shock wave propagationpreventing unit disposed in the communication pipe, communication pipeopening/closing valves disposed at both sides of the shock wavepropagation preventing unit, and a vacuum evacuation unit for vacuumprocessing the communication pipe, which is provided between the shockwave propagation preventing unit and a communication pipeopening/closing valve disposed close to the vacuum preparation chamberhaving a lower pressure, wherein the communication pipe is vacuumprocessed by the vacuum evacuation unit when both of the communicationpipe opening/closing valves are closed before the gate valve is openedsuch that a pressure of the communication pipe is made lower than thatof the chamber having a lower pressure, and the gate valve is openedafter opening the communication pipe opening/closing valve close to thechamber having a lower pressure and then opening the communication pipeopening/closing valve close to the chamber having a higher pressure tolet the chambers communicate with each other.

In accordance with the present invention, as described above, even ifthere is the pressure difference between the chambers, it is possible toprevent the particles from being swirled up along the shock waveoccurring when opening the communication pipe opening/closing valve. Forexample, when the communication pipe opening/closing valve disposedclose to the chamber having a lower pressure is opened, the pressure inthe communication pipe is lower than that in the chamber having a lowerpressure. Accordingly, a shock wave occurs in the communication pipe,and the shock wave remains in the communication pipe by the presence ofthe shock wave propagation preventing unit without propagating, therebypreventing the swirling up of particles. Further, although thecommunication pipe opening/closing valve disposed close to the chamberhaving a higher pressure is opened, a shock wave occurs in thecommunication pipe in the same way as in the above case, and the shockwave remains in the communication pipe by the presence of the shock wavepropagation preventing unit without propagating, thereby preventingparticles from being swirled up. Furthermore, since the pressuredifference between the chambers is reduced by opening the communicationpipe opening/closing valve, even though the gate valve is opened afterthat, a shock wave does not occur to thereby prevent the particles frombeing swirled up along the shock wave. Moreover, the communication pipecan be evacuated, whereby it is possible to prevent the communicationpipe from being contaminated by a corrosive gas.

Further, in the computer readable storage medium, it waits until atleast an extension time for end of opening to atmosphere elapses fromwhen the vacuum preparation chamber is made to communicate with theatmosphere by the opening-to-atmosphere unit. When the extension timefor end of opening to atmosphere has elapsed, if there is an instructionto open the gate valve, it is possible to open the gate valve accordingto the instruction.

In this case, it may wait until the extension time for end of opening toatmosphere elapses after the regulation delay time has elapsed from whenthe vacuum preparation chamber is made to communicate with theatmosphere by the opening-to-atmosphere unit. Further, if there is aninstruction to open the gate valve during after the regulation delaytime, from that point, it may wait until the extension time for end ofopening to atmosphere elapses. Meanwhile, if there is an instruction toopen the gate valve after the regulation delay time has elapsed, fromthat point, it may wait until the extension time for end of opening toatmosphere elapses. Accordingly, the process of opening to atmosphere inthe vacuum preparation chamber in accordance with the present inventioncan be employed without changing other steps in the conventionalsequence.

Further, let 1 Torr and 1 mTorr be 101325/760 Pa and 10⁻³×101325/760 Pa,respectively.

As described above, in accordance with the present invention, there areprovided a substrate processing apparatus, a program for performingoperation and control method thereof, and a computer readable storagemedium for storing the program capable of effectively preventingparticles from being swirled up in a chamber by suppressing a shock waveor convection caused when the gate valve is opened between chambers bymeans of a simple configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention willbecome apparent from the following description of preferred embodiments,given in conjunction with the accompanying drawings, in which:

FIG. 1 schematically shows a cross sectional view of a substrateprocessing apparatus in accordance with an embodiment of the presentinvention;

FIG. 2 shows a schematic configuration of gas piping of the load-lockchamber shown in FIG. 1;

FIG. 3 is a flowchart showing a conventional example of a first processof opening to atmosphere;

FIG. 4 depicts a broken-line graph showing timings when each valve isopened or closed in the process shown in FIG. 3;

FIG. 5 is a flowchart showing a first process of opening to atmospherein accordance with the present invention, which is performed by acontroller;

FIG. 6 depicts a broken-line graph showing timings when each valve isopened or closed in the process shown in FIG. 5;

FIG. 7 is a flowchart showing a conventional example of a second processof opening to atmosphere;

FIG. 8 depicts a broken-line graph showing timings when each valve isopened or closed in the process shown in FIG. 7;

FIG. 9 is a flowchart showing a second process of opening to atmospherein accordance with the present invention, which is performed by acontroller;

FIG. 10 depicts a broken-line graph showing timings when each valve isopened or closed in the process shown in FIG. 9;

FIG. 11 is a flowchart showing a backflow detecting process conductedwhen an acid evacuation valve shown in FIG. 2 is opened;

FIGS. 12A and 12B show an example of a unit for detecting the amount ofparticles.

FIG. 13 shows a relationship between a pressure difference betweenchambers and particle scattering probability;

FIG. 14 shows a shock wave preventing mechanism provided between aload-lock chamber and a processing chamber;

FIG. 15 shows a configuration of a Laval nozzle that is an example of ashock wave propagation preventing unit;

FIG. 16 shows a configuration of a Laval nozzle that is another exampleof a shock wave propagation preventing unit;

FIG. 17 schematically shows a configuration of a modified example of asubstrate processing apparatus including a shock wave preventingmechanism;

FIG. 18 shows a schematic configuration of a substrate processingapparatus provided with a vacuum processing unit including multiplechambers;

FIG. 19 is a flowchart showing a general example of a self-check processin the processing chamber; and

FIG. 20 shows an example of a self-check process in which the vacuumgauge employing the measuring device is not used.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described indetail with reference to the accompanying drawings. Like referencenumerals will be given to like parts and, further, a redundantdescription will be omitted.

First, there will be explained an operation and control method of asubstrate processing apparatus in accordance with preferred embodimentsof the present invention. One of substrate processing apparatuses forperforming a process on a substrate to be processed includes a transferchamber under the atmospheric pressure; a vacuum processing chamber forperforming a process on the substrate in a vacuum state; and a vacuumpreparation chamber, e.g., a load-lock chamber, disposed therebetweenand connected to them. In such a substrate processing apparatus, forexample, when the substrate to be processed is transferred between thetransfer chamber and the load-lock chamber, a process of opening toatmosphere for approximating an inner pressure of the load-lock chamberto the atmospheric pressure in the transfer chamber is carried out toreduce a pressure difference between the chambers before the gate valvebetween the transfer chamber and the load-lock chamber is opened.Hereinafter, operation and control methods of the substrate processingapparatus featuring the process of opening to atmosphere areexemplified.

(Configuration Example of Substrate Processing Apparatus)

A specific example of substrate processing apparatus to which operationand control methods of the substrate processing apparatus in accordancewith preferred embodiments of the present invention can be applied willbe explained with reference to the drawings. Here, a substrateprocessing apparatus, wherein at least one vacuum processing unit isconnected to a transfer chamber under the atmospheric pressure, will beexemplified. FIG. 1 schematically shows a cross sectional view of asubstrate processing apparatus in accordance with the presentembodiments. The substrate processing apparatus 100 includes one or morevacuum processing units 110 for performing various processes such asetching or film forming process on the substrate to be processed, forexample, a semiconductor wafer W (hereinafter, simply referred to as a“wafer”); and a transfer unit 120 for loading/unloading the wafer Winto/from the vacuum processing unit 110. The transfer unit 120 has atransfer chamber 130 which is commonly used when transferring the waferW.

In FIG. 1, for example, two vacuum processing units 110A and 110B aredisposed at a side of the transfer unit 120. The vacuum processing unit110A (110B) has a processing chamber 140A (140B) and a load-lock chamber150A (150B), connected to the processing chamber 140A (140B), that canbe evacuatable. The vacuum processing units 110A and 110B perform samekinds of processes or different kinds of processes on the wafers W inthe processing chambers 140A and 140B. The susceptor 142A (142B) formounting the wafer W thereon is installed in the processing chamber 140A(140B). Further, the number of the vacuum processing units 110 includingthe processing chamber 140 and the load-lock chamber 150 is not limitedto two and may be three or more.

The transfer chamber 130 of the transfer unit 120 is formed of ahorizontally lengthened box having an approximately rectangular section,wherein a nonreactive gas such as N₂ gas or clean air is circulated. Aplurality of cassette tables 132A, 132B and 132C are arranged at onelong side of the transfer chamber 130. The cassette tables 132A, 132Band 132C serve as substrate waiting ports for mounting cassettecontainers 134A, 134B and 134C. Although the three cassette containers134A, 134B and 134C are respectively mounted on the cassette tables132A, 132B and 132C in FIG. 1, the number of cassette tables or cassettecontainers is not limited thereto and may be one, two, four or more.

Each of the cassette containers 134A to 134C can accommodate therein upto, for example, 25 wafers W mounted in multiple levels at an equalpitch. Further, the cassette containers 134A to 134C are sealed andfilled with, for example, N₂ gas. Further, the wafer W can be loadedinto or unloaded from the transfer chamber 130 via gate valves 136A to136C.

A common transfer mechanism (atmospheric side transfer mechanism) 160which transfers the wafer W in a longitudinal direction of the transferchamber 130 (shown by an arrow in FIG. 1) is disposed in the transferchamber 130. The common transfer mechanism 160 is fixed on, for example,a base 162 and can be slidably moved on a guide rail (not shown)installed in a central portion of the transfer chamber 130 in thelongitudinal direction thereof by, e.g., a linear motor drivingmechanism. The common transfer mechanism 160 may be, for example, adouble-arm mechanism having two picks as shown in FIG. 1 or a single-armmechanism having one pick. Disposed at an end portion, i.e., one shortside, of the transfer chamber 130 is an orienter (pre-alignment stage)137 as a positioning mechanism for performing a positioning of thewafer. The orienter 137 has a rotatable table 138 and an optical sensor139 for optically detecting a peripheral portion of the wafer W. Theorienter 137 performs a position alignment by detecting a notch or anorientation flat of the wafer W.

The bases of the two load-lock chambers 150A and 150B are connected toanother long side of the transfer chamber 130 via the gate valves(atmospheric side gate valves) 152A and 152B capable of being opened orclosed, respectively. The processing chambers 140A and 140B areconnected to the leading ends of the load-lock chambers 150A and 150Bvia the gate valves (vacuum side gate valves) 144A and 144B capable ofbeing opened or closed, respectively.

A pair of buffer susceptors 154A and 156A (154B and 156B) fortemporarily mounting thereon the wafer W that is waiting is disposed inthe load-lock chamber 150A (150B). Here, let the buffer susceptors 154Aand 154B of the transfer chamber side be first buffer susceptors; andthe buffer susceptors 156A and 156B of the opposite side be secondbuffer susceptors. Further, an individual transfer mechanism (vacuumside transfer mechanism) 170A (170B) having a stretchable, bendable,revolvable and elevatable multi-joint arm is provided between the buffersusceptors 154A and 156A (154B and 156B). A pick 172A (172B) is disposedat the leading end of the individual transfer mechanism 170A (170B), andthe wafer W can be transferred between the first and the second buffersusceptor, i.e., between the buffer susceptors 154A and 156A (154B and156B), by using the pick 172A (172B). Further, loading/unloading of thewafer W is performed between the load-lock chamber 150A (150B) and theprocessing chamber 140A (140B) by using the individual transfermechanism 170A (170B).

The substrate processing apparatus 100 is provided with a controller 180for controlling operations of all components of the substrate processingapparatus, for example, valves of gas feed and gas evacuation pipes, tobe described later, connected to the load-lock chambers 150A and 150B aswell as the above-mentioned transfer mechanisms 160 and 170 and gatevalves 136, 144 and 152. The controller 180 includes a microcomputerthat forms a main body of the controller 180, a memory for storing,e.g., various data, and the like. Further, the controller 180 can beimplemented with a general purpose computer, e.g., PC (personalcomputer), which has, e.g., a CPU, a mother board (MB), a hard disk(HD), memories such as ROM and RAM, a CD/DVD drive and so on. In such acase, the process control can be carried out in a completely automatedmanner under the control of a control program or a software running onthe controller 180. Though not specifically depicted in FIG. 1, controlsignals are provided from the controller 180 to the components viacontroller lines (not shown). The control program can be directlyprogrammed on the controller 180 or can be programmed outside to beprovided thereto via, e.g., a network or the CD/DVD drive and thenstored in, e.g., the hard disk for the execution thereof.

(Gas Piping Configuration of Load-Lock Chamber)

Next, there will be described a gas piping configuration of theload-lock chamber in the vacuum processing unit with reference todrawings. FIG. 2 shows a schematic configuration of the gas piping ofthe load-lock chamber 150. Further, the gas piping configuration iscommon to both of the load-lock chambers 150A and 150B of the vacuumprocessing units 110A and 110B.

A nonreactive gas introducing unit is disposed at a gas feed side of theload-lock chamber 150 (for example, at an upper portion or a sideportion thereof). The nonreactive gas introducing unit includes a purgegas feeding pipe 181 for supplying a nonreactive gas (e.g., Ar gas or N₂gas) serving as a purge gas to the load-lock chamber 150. Control valves(purge valves) V1 and V2 arranged in parallel are inserted into thepurge gas feeding pipe 181 and serve as gas introduction valves. Thecontrol valves V1 and V2 control a flow rate of the purge gas. Forexample, the control valve V1 is used in a process of opening toatmosphere to be discussed later, and the control valve V2 is used whencontrolling an inner pressure of the load-lock chamber. Further, asingle control valve can be used instead of the control valves V1 and V2for the purge gas.

Further, an atmospheric pressure state detecting unit for detecting anatmospheric pressure state is connected to the gas feed side of theload-lock chamber 150. Specifically, an atmospheric pressure switch 187is connected to the load-lock chamber 150 via a connecting pipe 182 forthe atmospheric pressure switch 187. Further, a manometer 188 isconnected to the connecting pipe 182 for the atmospheric pressure switch187 via a protection valve V3 and a Pirani vacuum gauge (Pirani gauge)189 is also connected to the connecting pipe 182. The atmosphericpressure switch 187 includes a crystal gauge and the like. The manometer188 is formed of, for example, a capacitance manometer (diaphragm vacuumgauge). For instance, a Conventron vacuum gauge may be employed insteadof the Pirani gauge 189.

On the other hand, a unit of opening to atmosphere is disposed at anevacuation side of the load-lock chamber 150, for example, at a bottomportion of the load-lock chamber 150. The unit of opening to atmosphereincludes a relief pipe (atmosphere communicating pipe) 183, which makesthe load-lock chamber 150 communicate with the atmosphere via a reliefvalve (valve of opening to atmosphere) V4. An air feeding pipe 184 forsupplying purge air is connected to the relief pipe (pipe of opening toatmosphere) 183, specifically, between the load-lock chamber 150 and therelief valve V4. A control valve V5 for controlling an air flow rate isinserted in the air feeding pipe 184.

Further, a vacuum evacuation unit is disposed at the evacuation side ofthe load-lock chamber 150. The vacuum evacuation unit is provided with avacuum evacuation pipe 185 for evacuating the load-lock chamber 150 tovacuum. A main evacuation valve V6 and a slow evacuation valve V7arranged in parallel are inserted in the vacuum evacuation pipe 185, andthe vacuum evacuation pipe 185 is connected to a vacuum pump 190 such asa dry pump. The main evacuation valve V6 is used for evacuating a largeamount of gas at once, and the slow evacuation valve V7 is used for afine control of the evacuation flow rate.

Further, a corrosive gas evacuation unit is disposed at the evacuationside of the load-lock chamber 150. The corrosive gas evacuation unitincludes an acid evacuation pipe 186 connected between the load-lockchamber 150 and the evacuation valves V6 and V7. In the middle of theacid evacuation pipe 186, there is installed an acid evacuation valve V8that can be controlled for evacuating acid in the load-lock chamber 150when a corrosive gas (e.g., Cl₂ and HCl) is used as a processing gas onthe wafer W. Specifically, a processing gas such as the corrosive gasthat can enter the load-lock chamber 150 when the wafer W is unloadedfrom the processing chamber 140, water that can enter it from theatmosphere and the like are evacuated via the acid evacuation valve V8.The acid evacuation pipe 186 is connected to the evacuation equipment offactory in which the vacuum processing unit is installed. The acidevacuation pipe 186 is connected to a Manostar gauge 192 which is one ofthe backflow detecting units.

The above-mentioned control valves V1 to V8 are controlled by, e.g., thecontroller 180 to thereby perform a pressure control of the load-lockchamber 150. The pressure control is performed in a process of openingto atmosphere when the gate valve 152 is opened in the load-lock chamber150. A backflow detecting process is carried out such that the Manostargauge 192 is monitored and when a backflow is detected, it is notifiedby the controller 180. The process of opening to atmosphere and backflowdetecting process will be described later.

(Operations of Substrate Processing Apparatus)

Hereinafter, there will be explained operations of the substrateprocessing apparatus having the above-mentioned configuration withreference to the drawings. First, the wafer W to be processed isunloaded from one of the cassette containers 134A to 134C by the commontransfer mechanism 160. The wafer W unloaded by the common transfermechanism 160 is transferred to the orienter 137 and mounted on therotatable table 138, and then a positioning of the wafer W is performed.The positioned wafer W is taken back and supported by the commontransfer mechanism 160. The wafer W is transferred right in front of theload-lock chamber 150A (150B) of the vacuum processing unit 110A (110B)for performing a process on the wafer W. Then, the gate valve 152A(152B) is opened and the wafer W supported by the common transfermechanism 160 is loaded into the load-lock chamber 150A (150B) from thetransfer chamber 130. When loading of the wafer W into the load-lockchamber 150A (150B) is finished, the gate valve 152A (152B) is closed.

When the gate valve 144A (144B) is opened, the wafer W loaded into theload-lock chamber 150A (150B) is transferred into the processing chamber140A (140B) by the individual transfer mechanism 170A (170B). Whenloading of the wafer W into the processing chamber 140A (140B) isfinished, the gate valve 144A (144B) is closed. Processing of the waferW is started by using, for example, a corrosive gas as a processing gasin the processing chamber 140A (140B).

Thereafter, when the processing of the wafer W is finished in theprocessing chamber 140A (140B), the gate valve 144A (144B) is opened andthe wafer W is loaded into the load-lock chamber 150A (150B) by theindividual transfer mechanism 170A (170B). When loading of the wafer Winto the load-lock chamber 150A (150B) is finished, the gate valve 144A(144B) is closed and the wafer W is transferred into the transferchamber 130. That is, when the gate valve 152A (152B) is opened, theprocessed wafer W loaded into the load-lock chamber 150A (150B) istransferred into the transfer chamber 130 from the load-lock chamber150A (150B) by the common transfer mechanism 160, and the gate valve152A (152B) is closed.

In the above-mentioned operations, when the wafer W is transferredbetween the load-lock chamber 150A (150B) and the transfer chamber 130under the atmospheric pressure, a process of opening to atmosphere isperformed in the load-lock chamber 150A (150B) before the gate valve152A (152B) is opened.

(Process of Opening to Atmosphere in Load-Lock Chamber)

Hereinafter, a process of opening to atmosphere performed in theload-lock chamber 150A (150B) in accordance with the embodiment of thepresent invention will be explained in detail by comparing it with aconventional process with reference to the drawings. Further, theprocess of opening to atmosphere in accordance with the embodiment ofthe present invention is performed by controlling the respective valvesby a controller 180 that is operated based on a specified program.

As the process of opening to atmosphere, there are first and secondprocesses of opening to atmosphere. In the first process of opening toatmosphere, when the atmospheric pressure is formed in the load-lockchamber by introducing thereto a nonreactive gas such as N₂ gas servingas a purge gas, steps of opening the relief valve, closing the purgevalve and opening the gate valve between the transfer chamber and theload-lock chamber are performed sequentially. In the second process ofopening to atmosphere, wherein a throughput of the substrate processingapparatus is taken more seriously, the gate valve is made to be openedafter the relief valve is opened, and the purge valve is closed when thegate valve is opened. The process of opening to atmosphere in accordancewith the present invention can be applied to both the first and thesecond process of opening to atmosphere, and respective cases will bedescribed separately.

(First Process of Opening to Atmosphere)

First, a conventional example of the first process of opening toatmosphere will be explained for comparing with that of the presentinvention. FIG. 3 is a flowchart showing the conventional example of thefirst process of opening to atmosphere, and FIG. 4 depicts controlstates of respective valves in the process shown in FIG. 3. FIG. 4 is abroken-line graph showing timings when each valve is opened or closed.Further, when broken lines overlap with each other, they are drawn asslightly separated lines for distinction.

As shown in FIGS. 3 and 4, in the conventional example of the firstprocess of opening to atmosphere, first, at step S110, the control valve(purge valve) V1 shown in FIG. 2 is opened and a nonreactive gas such asN₂ gas serving as a purge gas is introduced into the load-lock chamber150. Then, at step S120, it is determined whether or not the load-lockchamber 150 is under the atmospheric pressure, for example, as follows.If the atmospheric pressure switch 187 shown in FIG. 2 is turned on and,at the same time, the Pirani gauge 189 indicates the atmosphericpressure (760 Torr), it is determined that the pressure of the load-lockchamber 150 becomes same as the atmospheric pressure.

At step S120, if it is determined that the pressure of the load-lockchamber 150 becomes same as the atmospheric pressure at a time pointt₁₁, the process proceeds to step S130. At step S130, when a specifiedtime period T₁₁ has elapsed from the time point t₁₁ as shown in FIG. 4,the relief valve V4 is opened to make the load-lock chamber 150communicate with the atmosphere.

Then, at step S140, when a specified time period T₁₂ has elapsed fromthe time point t₁₁, the control valve (purge valve) V1 is closed at atime point t₁₃ to stop introducing the purge gas. Subsequently, at stepS150, it waits till an extension time for end of opening to atmosphereT₁₃ elapses from the time point t₁₃. When the extension time for end ofopening to atmosphere T₁₃ has elapsed, the process of opening toatmosphere is finished and, from that point, it is possible to open thegate valve 152.

At step S150, if it is determined that the extension time for end ofopening to atmosphere T₁₃ has elapsed, the process proceeds to step S160to wait for an instruction to open the gate valve 152. Then, at stepS160, if it is determined that there is the instruction to open the gatevalve 152, the process proceeds to step S170 where the instruction toopen the gate valve 152 is accepted to open the gate valve 152. When thegate valve 152 is opened, the process proceeds to step S180 where theacid evacuation valve V8 is opened to thereby start the evacuationperformance and the whole process of opening to atmosphere is finished.For example, this process is for evacuating a processing gas such ascorrosive gas (e.g., Cl₂ and HCl), which enters the load-lock chamber150 when the wafer W is unloaded from the processing chamber 140.Practically, the pressure in the load-lock chamber 150 is made higherthan that in the processing chamber 140 when the wafer W is transferredfrom the processing chamber 140 such that a small convection occurs fromthe load-lock chamber 150 to the processing chamber 140 in order toprevent the corrosive gas from entering the load-lock chamber 150 fromthe processing chamber 140. However, the corrosive gas can enter theload-lock chamber 150 by being attached to the wafer W.

As described above, in the conventional first process of opening toatmosphere, after the load-lock chamber 150 becomes open to theatmosphere, the pressure of the load-lock chamber 150 is also madehigher than that of the transfer chamber 130 by introducing the purgegas into the load-lock chamber 150 to thereby prevent an outside airfrom entering it. Accordingly, since contaminants such as water includedin the outside air can be prevented from entering the load-lock chamber150, it is possible to prevent cross contamination to the wafer W.

However, recently, for example, due to the sealing improvement of amaintenance door in the load-lock chamber 150, airtightness of theload-lock chamber 150 is further enhanced. Nevertheless, conventionally,since the time period T₁₂ set to be elapsed until the introduction ofthe purge gas is stopped is fixed as a constant as shown in FIG. 4, thepressure of the load-lock chamber 150 tends to become needlessly higherthan that of the transfer chamber 130 due to the introduction of thepurge gas. Consequently, when the gate valve 152 between the load-lockchamber 150 and the transfer chamber 130 is opened, a shock wave orrapid convection could be generated. If a shock wave or rapid convectionoccurs, it leads to a problem such that particles tend to be swirled uptherealong in the load-lock chamber 150.

Further, in the conventional first process of opening to atmosphere,since the acid evacuation valve V8 is closed until the gate valve 152 isopened, the load-lock chamber 150 communicates with the atmosphere byopening the relief valve V4. Accordingly, for example, in case when therelief pipe 183 communicates with the transfer chamber 130, thecorrosive gas remaining in the load-lock chamber 150 can flow into thetransfer chamber 130. The corrosive gas which flows into the transferchamber 130 causes parts of mechanisms in the transfer chamber 130 to becorroded.

Therefore, in the process of opening to atmosphere in accordance withthe present invention, timings of closing the control valve (purgevalve) V1 and opening the acid evacuation valve V8 can be freely set.Accordingly, for example, at a time point when the pressure of theload-lock chamber 150 becomes same as the atmospheric pressure,simultaneously, the control valve (purge valve) V1 is closed to stopintroducing the purge gas, and the acid evacuation valve V8 is opened.As a result, it is prevented that the pressure of the load-lock chamber150 becomes needlessly increased and, further, the corrosive gasremaining in the load-lock chamber 150 can be evacuated in advancebefore the gate valve 152 is opened.

(First Process of Opening to Atmosphere in Accordance with the PresentInvention)

Hereinafter, an example of a first process of opening to atmosphere inaccordance with the present invention will be explained with referenceto FIGS. 5 and 6. In this example, at a time point when the pressure ofthe load-lock chamber 150 becomes same as the atmospheric pressure, thecontrol valve (purge valve) V1 is closed to stop introducing the purgegas and the acid evacuation valve V8 is opened. FIG. 5 is a flowchartshowing a first process of opening to atmosphere in accordance with thepresent invention, which is performed by a controller. FIG. 6 depictscontrol states of respective valves in the process shown in FIG. 5. FIG.6 is, similarly to FIG. 4, a broken-line graph showing timings when eachvalve is opened or closed. Further, when broken lines overlap eachother, they are drawn as slightly separated lines for distinction.

The process of opening to atmosphere in accordance with the presentinvention is performed based on a program by the controller 180 asfollows. That is, as shown in FIGS. 5 and 6, first, at step S210, thecontrol valve (purge valve) V1 shown in FIG. 2 is opened and anonreactive gas such as N₂ gas serving as a purge gas is introduced intothe load-lock chamber 150. Then, at step S220, it is determined whetheror not the load-lock chamber 150 is under the atmospheric pressure, forexample, in the same way as in step S120 shown in FIG. 3. Namely, if theatmospheric pressure switch 187 shown in FIG. 2 is turned on and, at thesame time, the Pirani gauge 189 indicates the atmospheric pressure (760Torr), it is determined that the pressure of the load-lock chamber 150becomes same as the atmospheric pressure.

At step S220, if it is determined that the pressure of the load-lockchamber 150 becomes same as the atmospheric pressure at a time pointt₂₁, for example, simultaneously, the process proceeds to step S230. Atstep S230, as shown in FIG. 6, the control valve (purge valve) V1 isclosed to stop the introduction of the purge gas. At the same time, atstep S240, the acid evacuation valve V8 is opened to start at an earlystage evacuating the corrosive gas that enters the load-lock chamber150.

Then, the process proceeds to step S250, wherein when a specified timeperiod T₂₁ elapses from the time point t₂₁, as shown in FIG. 6, therelief valve V4 is opened such that the load-lock chamber 150communicates with the atmosphere.

Subsequently, at step S260, it waits until a regulation delay time T₂₂elapses from the time point t₂₂ such that the gate valve 152 can beopened at the same time as the gate valve is opened in the conventionalsequence. Accordingly, a time period (shown in FIG. 6) from the timepoint t₂₁ when the load-lock chamber 150 becomes open to the atmosphereto the time point when the gate valve is opened can be made same as atime period (shown in FIG. 4) from the time point t₁₁ when the load-lockchamber 150 becomes open to the atmosphere to the time point when thegate valve is opened. Thus, the process of opening to atmosphere inaccordance with the present invention can be employed without changingother steps in the conventional sequence. Further, the step where itwaits until the regulation delay time elapses is not necessarilyrequired. By omitting the step, the gate valve 152 can be opened earlierthan before. Accordingly, the total time for the sequence can beshortened.

At step S260, if it is determined that the regulation delay time T₂₂ haselapsed, the process proceeds to step S270 where it waits until anextension time for end of opening to atmosphere T₂₃ elapses. When theextension time for end of opening to atmosphere T₂₃ elapses, opening toatmosphere is finished and it is possible to open the gate valve 152between the transfer chamber 130 and the load-lock chamber 150.

At step S270, when it is determined that the extension time for end ofopening to atmosphere T₂₃ has elapsed, the process proceeds to step S280to wait for an instruction to open the gate valve 152. Then, at stepS280, when it is determined that there is the instruction to open thegate valve 152, the process proceeds to step S290 where the instructionto open the gate valve 152 is accepted to open the gate valve 152. Thus,the whole process of opening to atmosphere is finished.

As described above, in the first process of opening to atmosphere inaccordance with the present invention, the control valve (purge valve)V1 is closed right after the pressure of the load-lock chamber 150becomes same as the atmospheric pressure. By such a simple change in thesequence, it is prevented that the pressure of the load-lock chamber 150becomes needlessly increased. Consequently, it is prevented that a shockwave or rapid convection occurs when the gate valve 152 is opened,thereby preventing particles from being swirled up in the load-lockchamber 150.

Further, the acid evacuation valve V8 is opened early before the gatevalve 152 is opened, whereby the corrosive gas remaining in theload-lock chamber 150 can be evacuated in advance. Accordingly, althoughthe relief valve V4 is opened after that, the corrosive gas can beprevented from flowing into, e.g., the transfer chamber 130 via therelief valve V4. Resultantly, it can be prevented that parts ofmechanisms in the transfer chamber 130 are corroded.

(Second Process of Opening to Atmosphere)

Next, a conventional example of a second process of opening toatmosphere will be explained for comparing it with the presentinvention. FIG. 7 is a flowchart showing the conventional example of thesecond process of opening to atmosphere, and FIG. 8 depicts controlstates of respective valves in the process shown in FIG. 7. FIG. 8 is,similarly to FIG. 4, a broken-line graph showing timings when each valveis opened or closed. Further, when broken lines overlap each other, theyare drawn as slightly separated lines for distinction.

As shown in FIGS. 7 and 8, in the conventional example of the secondprocess of opening to atmosphere, first, at step S310, the control valve(purge valve) V1 shown in FIG. 2 is opened and a nonreactive gas such asN₂ gas serving as a purge gas is introduced into the load-lock chamber150. Subsequently, as step S320, it is determined whether or not theload-lock chamber 150 is under the atmospheric pressure in the same wayas in step S120 shown in FIG. 3. At step S320, if it is determined thatthe pressure of the load-lock chamber 150 becomes same as theatmospheric pressure at a time point t₃₁, the process proceeds to stepS330. At step S330, when a specified time period T₃₁ elapses from thetime point t₃₁, the relief valve V4 is opened to let the load-lockchamber 150 communicate with the atmosphere. In the second process ofopening to atmosphere, at a time point t₃₂ when the relief valve V4 isopened, the opening to atmosphere is finished and from that point, it ispossible to accept an instruction to open the gate valve 152.Thereafter, regardless of the instruction to open the gate valve 152,when a specified time period T₃₂ elapses, the control valve (purgevalve) V1 is closed to stop introducing the purge gas.

Then, at step S340, it is determined whether or not a purge end time T₃₂has elapsed from the time point t₃₂. If it is determined that the purgeend time T₃₂ has not elapsed at step S340, the process proceeds to stepS410 where it is determined whether or not there is an instruction toopen the gate valve 152.

At step S410, if it is determined that there is no instruction to openthe gate valve 152, the process returns to step S340. While there is noinstruction to open the gate valve 152, at step S340, if it isdetermined that the purge end time T₃₂ has elapsed, the process proceedsto step S350 where the control valve (purge valve) V1 is closed to stopintroducing the purge gas.

Then, at step S360, if it is determined that there is an instruction toopen the gate valve 152, the instruction is accepted and the processproceeds to step S370 where it waits until an extension time for end ofopening to atmosphere T₃₃ elapses. At step S370, if it is determinedthat the extension time for end of opening to atmosphere T₃₃ haselapsed, the process proceeds to step S380 where the gate valve 152 isopened. When the gate valve 152 is opened, the process proceeds to stepS390 where the acid evacuation valve V8 is opened, whereby theevacuation performance of, e.g., corrosive gas is carried out and thewhole process of opening to atmosphere is finished.

In contrast, in a state where the purge end time T₃₂ has not elapsed, ifit is determined that there is an instruction to open the gate valve 152at step S410, the instruction is accepted and the process proceeds tostep S420 where the control valve (purge valve) V1 is closed to stopintroducing the purge gas. Then, the process proceeds to step S370. Ifit is determined that an extension time for end of opening to atmosphereT₃₃ has elapsed at step S370, the process proceeds to step S380 wherethe gate valve is opened. Then, at step S390, the acid evacuation valveV8 is opened, whereby the evacuation process of, e.g., corrosive gas isperformed and the whole process of opening to atmosphere is finished.

As described above, in the conventional second process of opening toatmosphere, if there is no instruction to open the gate valve 152 duringthe purge end time T₃₂, the control valve (purge valve) V1 is closed tostop introducing the purge gas when the purge end time T₃₂ elapses. Onthe contrary, if there arrives an instruction to open the gate valve 152during the purge end time T₃₂, at that time, the control valve (purgevalve) V1 is closed to stop introducing the purge gas. Accordingly, thegate valve 152 can be opened earlier than the first process of openingto atmosphere.

Also in the conventional second process of opening to atmosphere, in thesame manner as in the first process of opening to atmosphere, after theload-lock chamber 150 becomes open to the atmosphere, the pressure ofthe load-lock chamber 150 is made higher than that of the transferchamber 130 by introducing the purge gas into the load-lock chamber 150to thereby prevent an outside air from entering it. Accordingly, sincecontaminants such as water included in the outside air can be preventedfrom entering the load-lock chamber 150, it is possible to prevent crosscontamination to the wafer W.

In the conventional second process of opening to atmosphere, a timing ofclosing the control valve (purge valve) V1 may become earlier than thatof the conventional first process of opening to atmosphere. However, theinstruction to open the gate valve 152 cannot be accepted unless atleast the specified time period T₃₁ from the time point t₃₁ has elapsedand the relief valve V4 is opened thereafter. Thus, the pressure of theload-lock chamber 150 tends to become needlessly higher than that of thetransfer chamber 130 until the introduction of the purge gas is stopped.Consequently, when the gate valve 152 is opened, a shock wave or rapidconvection can be generated, whereby it leads to the same problem asthat in the conventional first process of opening to atmosphere, namely,having particles to swirl up therealong in the load-lock chamber 150.

Further, in the conventional second process of opening to atmosphere,since the acid evacuation valve V8 is closed until the gate valve 152 isopened, the load-lock chamber 150 communicates with the atmosphere byopening the relief valve V4. Accordingly, for example, in case that therelief pipe 183 communicates with the transfer chamber 130, thecorrosive gas remaining in the load-lock chamber 150 can flow into thetransfer chamber 130. As a result, there also occurs the same problem asthat in the conventional first process of opening to atmosphere, namely,that parts of mechanisms in the transfer chamber 130 may be corroded.

Therefore, in the second process of opening to atmosphere of the presentinvention, similarly, timings of closing the control valve (purge valve)V1 and opening the acid evacuation valve V8 can be freely set.Accordingly, for example, at a time point when the pressure of theload-lock chamber 150 becomes same as the atmospheric pressure, thecontrol valve (purge valve) V1 is closed to stop introducing the purgegas and the acid evacuation valve V8 is opened. Resultantly, it isprevented that the pressure of the load-lock chamber 150 becomesneedlessly increased and, further, the corrosive gas remaining in theload-lock chamber 150 can be evacuated in advance before the gate valve152 is opened.

(Second Process of Opening to Atmosphere in Accordance with the PresentInvention)

Hereinafter, an example of the second process of opening to atmospherein accordance with the present invention will be explained withreference to FIGS. 9 and 10. In this example, at a time point when thepressure of the load-lock chamber 150 becomes same as the atmosphericpressure, the control valve (purge valve) V1 is closed to stopintroducing the purge gas to the load-lock chamber 150 and the acidevacuation valve V8 is opened. FIG. 9 is a flowchart showing the exampleof the second process of opening to atmosphere in accordance with thepresent invention, which is performed by a controller. FIG. 10 depictscontrol states of respective valves in the process shown in FIG. 9. FIG.10 is, similarly to FIG. 4, a broken-line graph showing timings wheneach valve is opened or closed. Further, when broken lines overlap witheach other, they are drawn as slightly separated lines for distinction.

The process of opening to atmosphere in accordance with the presentinvention is performed based on a program by the controller 180 asfollows. That is, as shown in FIGS. 9 and 10, first, at step S510, thecontrol valve (purge valve) V1 shown in FIG. 2 is opened and anonreactive gas such as N₂ gas serving as a purge gas is introduced intothe load-lock chamber 150. Then, at step S520, it is determined whetheror not the load-lock chamber 150 is under the atmospheric pressure, forexample, in the same way as in step S120 shown in FIG. 3.

At step S520, if it is determined that the pressure of the load-lockchamber 150 becomes same as the atmospheric pressure at a time pointt₄₁, for example, simultaneously, the process proceeds to step S530. Atstep S530, as shown in FIG. 10, the control valve (purge valve) V1 isclosed to stop the introduction of the purge gas. At the same time, atstep S540, the acid evacuation valve V8 is opened to start, at an earlystage, evacuating the corrosive gas that enters the load-lock chamber150.

Then, the process proceeds to step S550, wherein when a specified timeperiod T₄₁ elapses from the time point t₄₁, as shown in FIG. 10, therelief valve V4 is opened such that the load-lock chamber 150 starts tocommunicate with the atmosphere.

Subsequently, at step S560, it is determined whether or not a regulationdelay time T₄₂ has elapsed from the time point t₄₂. The regulation delaytime is introduced to make the gate valve 152 be opened at the same timeas the gate valve is opened in the conventional sequence shown in FIGS.7 and 8. Accordingly, a time period from the time point t₄₁, shown inFIG. 10, when the load-lock chamber 150 becomes open to the atmosphereto the time point when the gate valve is opened can be made equal to thetime period from the time point t₃₁, shown in FIG. 8, when the load-lockchamber 150 becomes open to the atmosphere to the time point when thegate valve is opened. Thus, the process of opening to atmosphere inaccordance with the present invention can be applied without changingother steps in the conventional sequence. Further, the step where itwaits until a regulation delay time elapses is not necessarily required.By omitting the step, the gate valve 152 can be opened earlier thanever. Accordingly, the total time for the sequence can be shortened.

At step S560, if it is determined that the regulation delay time T₄₂ hasnot elapsed, the process proceeds to step S600 where it is determinedwhether or not there is the instruction to open the gate valve 152. Atstep S600, when it is determined that there is no instruction to openthe gate valve 152, the process returns to step S560. While there is noinstruction to open the gate valve 152, at step S560, when it isdetermined that the regulation delay time T₄₂ has elapsed, the processproceeds to step S570 where it is determined whether or not there is aninstruction to open the gate valve 152.

Then, at step S570, if it is determined that there is an instruction toopen the gate valve 152, the instruction is accepted and the processproceeds to step S580 where it waits until an extension time for end ofopening to atmosphere T₄₃ elapses. At step S580, if it is determinedthat the extension time for end of opening to atmosphere T₄₃ haselapsed, the process proceeds to step S590 where the gate valve 152 isopened, and the whole process of opening to atmosphere is finished.

In contrast, in a state where the regulation delay time T₄₂ has notelapsed, when it is determined that there is an instruction to open thegate valve 152 at step S600, the instruction is accepted and the processproceeds to step S580. When it is determined that an extension time forend of opening to atmosphere T₄₃ has elapsed at step S580, the processproceeds to step S590 where the gate valve 152 is opened, and the wholeprocess of opening to atmosphere is finished.

As described above, in the second process of opening to atmosphere inaccordance with the present invention, the control valve (purge valve)V1 is closed right after the pressure of the load-lock chamber 150becomes same as the atmospheric pressure. By such a simple change in thesequence, it can be prevented that the pressure of the load-lock chamber150 becomes needlessly increased. Consequently, a shock wave or rapidconvection is prevented from occurring when the gate valve 152 isopened, thereby preventing particles from being swirled up in theload-lock chamber 150.

Further, the acid evacuation valve V8 is opened in advance withoutwaiting for opening the gate valve 152, whereby the corrosive gasremaining in the load-lock chamber 150 can be evacuated in advance.Accordingly, although the relief valve V4 is opened after that, thecorrosive gas can be prevented from flowing into the transfer chamber130 via the relief valve V4. Resultantly, it can be prevented that partsof mechanisms in the transfer chamber 130 are corroded.

Moreover, in the processes of opening to atmosphere in accordance withthe present invention, as shown in FIGS. 5 and 9, at a time point whenthe pressure of the load-lock chamber 150 becomes same as theatmospheric pressure, simultaneously, the control valve (purge valve) V1is closed to stop introducing the purge gas into the load-lock chamber150 and the acid evacuation valve V8 is opened. But, the presentinvention is not limited thereto. In the present invention, timings ofclosing the control valve (purge valve) V1 and opening the acidevacuation valve V8 can be freely set. Depending on setting of thetimings, the control valve (purge valve) V1 is closed and, somewhatlater, the acid evacuation valve V8 is opened. Further, the pressure ofthe load-lock chamber 150 becomes same as the atmospheric pressure and,somewhat later, it is also possible to close the control valve (purgevalve) V1 and open the acid evacuation valve V8. In order to preventparticles from being swirled up in the load-lock chamber 150 when thegate valve 152 is opened, it is desirable that those timings are setsuch that the inner pressure of the load-lock chamber 150 does notbecome excessively higher than the atmospheric pressure by anintroduction of the purge gas or an evacuation.

(Backflow Detecting Process when Acid Evacuation Valve is Opened)

Hereinafter, in the process of opening to atmosphere in accordance withthe present invention, there will be described a backflow detectingprocess performed when the acid evacuation valve is opened withreference to the drawings. In the present invention, as shown in FIGS. 5and 9, at a time point when the pressure of the load-lock chamber 150becomes same as the atmospheric pressure, that is, at an early statewhere the relief valve V4 or the gate valve 152 is not opened yet, thecontrol valve (purge valve) V1 is closed and the acid evacuation valveV8 is opened. Accordingly, a backflow can occur momentarily in the acidevacuation valve 186, but such a backflow will be controlled after aspecified time period passes.

However, when a backflow detecting unit, e.g., the Manostar gauge 192,detects a backflow in the acid evacuation pipe 186, it is notified by,e.g., a buzzer. Further, depending on an error process performed when abackflow occurs, the acid evacuation valve V8 may be forced to beclosed.

Thus, in the present invention, when the acid evacuation valve V8 isopened, a backflow detecting process shown in FIG. 11 is conducted,wherein although a backflow can occur momentarily in the acid evacuationvalve 186, an error process is not performed if the backflow becomescontrolled within a specified time period.

In the backflow detecting process shown in FIG. 11, when the acidevacuation valve V8 is opened, at step S710, it is determined whether ornot a backflow is detected in the acid evacuation pipe 186 by thebackflow detecting unit, e.g., the Manostar gauge 192. If it isdetermined that a backflow is not detected at step S710, the processproceeds to step S720 where it is determined whether or not a specifiedtime period, for example, 3 seconds, has elapsed. If the specified timeperiod has not elapsed, the process returns to step S710. If thebackflow is not detected within the specified time period and, further,it is determined that the specified time period has elapsed at stepS720, the backflow detecting process is finished. The specified timeperiod is, preferably, a time period during which the backflow willbecome controlled even though the backflow occurs momentarily, whereinthe time period may be obtained based on the experimental results. But,since there is a difference depending on the substrate processingapparatus, preferably, the specified time period of detecting thebackflow may be freely set. Specifically, the specified time period canbe set between 0 to 10 seconds.

In contrast, if it is determined that a backflow is detected at stepS710, the process proceeds to step S730 where it is determined whetheror not the specified time period has elapsed. If it is determined thatthe specified time period has not elapsed at step S730, the processreturns to step S710 where the backflow is kept being detected until thespecified time period passes. Then, when it is determined that thespecified time period has elapsed at step S730, the process proceeds tostep S740 where it is determined whether or not the backflow is undercontrol. For example, in case that the backflow is not detected afterthe specified time period passes, it is determined that the backflow isunder control. On the contrary, in case that the backflow is stilldetected after the specified time period has elapsed, it is determinedthat the backflow is not under control.

If it is determined that the backflow is under control at step S740, thebackflow detecting process is finished, whereas if it is determined thatthe backflow is not under control at step S740, the process proceeds tostep S750 where the error process is performed. As the error process,notification is done by, e.g., a buzzer and, also, the acid evacuationvalve V8 is forced to be closed.

In such a backflow detecting process, although the backflow is detectedmomentarily in the acid evacuation pipe 186, the error process is notconducted if the backflow becomes controlled within the specified timeperiod. Accordingly, when the acid evacuation valve V8 is opened earlybefore the gate valve 152 is opened in the present invention, it ispossible to avoid a practical problem such as the one that the acidevacuation valve V8 is closed just simply because a momentary backflowhas occurred in the acid evacuation pipe 186.

(Verification on Swirling Up of Particles)

As described above, in case that the process of opening to atmosphereperformed in the load-lock chamber in accordance with the presentinvention is applied to the substrate processing apparatus shown in FIG.1, the timings of opening/closing the purge valve or the acid evacuationvalve can be controlled such that particles can be prevented from beingswirled up due to a pressure difference between the load-lock chamberand the transfer chamber when the gate valve is opened.

The swirling up of particles is caused by a shock wave or rapidconvection occurring when the gate valve is opened between chambershaving a pressure difference, for example, between the transfer chamberand the load-lock chamber or between the processing chamber and theload-lock chamber. For example, the shock wave propagates instantly inthe chamber, thereby causing a rapid flow. Accordingly, the particlesare detached from walls of the chamber and swirled up in the chamber.

The shock wave occurs under a certain condition such as a condition on amagnitude of a pressure difference between chambers. Thus, swirling upof the particles can be generated by the shock wave depending on thepressure difference.

Hereinafter, there will be explained results of an experiment on how thepressure difference between the chambers affects the swirling up ofparticles with reference to drawings. Here, various pressure differencesare formed between the processing chamber 140 and the load-lock chamber150 shown in FIG. 1, and an amount of particles swirling up in theprocessing chamber 140 when the gate valve 144 is opened is detected.

First, a unit for detecting the amount of particles, which is used inthe present experiment, is described. FIGS. 12A and 12B are respectivelya perspective view and a cross sectional view of an example of a unitfor detecting the amount of particles provided in the processing chamber140. As shown in FIG. 12A, the unit for detecting the amount ofparticles includes a laser light source 210 such as a laser lightirradiating unit; slits 220 and 230; a light extinction device 240 forextinguishing the laser light from the laser light source 210; and alight receiving unit 250 such as CCD camera. Windows 148, formed ofquartz, for transmitting light are disposed in a portion of the wall ofthe processing chamber 140. As shown in FIG. 12B, a pair of the windows148 is disposed at positions such that they are aligned with the laserlight penetrating through the processing chamber 140 from the laserlight source 210 and a position where the light receiving unit 250 canreceive light scattered by particles in the processing chamber 140.

The laser light from the laser light source 210 is illuminated into theprocessing chamber 140 through the slit 220 and one of the pair of thewindows 148. Then, the laser light passes through the processing chamber140 and is projected onto the light extinction device 240 through theother of the pair of the windows 148 and the slit 230. At this time,scattered light caused by particles is observed by the light receivingunit 250 via the other of windows 148.

To perform an experiment by using the particle detecting device,particle powder is attached on the bottom surface of a gas feed unit 146in the processing chamber 140 and the pressures of the load-lock chamber150 and the processing chamber 140 are variously changed. Then,scattering of particles when the gate valve 144 is opened is observed bythe light receiving unit 250 and scattering probability is examined byrepeatedly performing the process multiple times. FIG. 13 shows theresult of the experiment, that is, scattering probability of particlesobtained by setting the pressure of the processing chamber 140 in arange disclosed in a right and upper column of FIG. 13 over respectivepressures of the load-lock chamber 150. In FIG. 13, a horizontal axisstands for the pressure of the load-lock chamber 150 and a vertical axisrepresents scattering probability of particles.

Let the pressure of the processing chamber 140 shown in the right andupper column be P1 and the pressure of the load-lock chamber 150 on thehorizontal axis be P2. According to the result of the experiment shownin FIG. 13, in case that P1 is 0.1 mTorr, the particles begin to scatterwhen P2 is about 125 mTorr, scattering probability increases inproportion as P2 rises, and the particles are scattering at aprobability of 100% when P2 is more than about 175 mTorr. In case thatP1 is 14 mTorr, the particles begin to scatter when P2 is about 100mTorr, scattering probability increases in proportion as P2 rises, andthe particles are scattering at a probability of 100% when P2 is morethan about 275 mTorr.

Further, in case that P1 is 100 mTorr, the particles begin to scatterwhen P2 is about 225 mTorr, scattering probability increases inproportion as P2 rises, and the particles are scattering at aprobability of 100% when P2 is more than about 450 mTorr. In case thatP1 is 200 mTorr, the particles begin to scatter when P2 is about 400mTorr, scattering probability increases in proportion as P2 rises, andthe particles are scattering at a probability of 100% when P2 is morethan about 525 mTorr.

From the results, the following conclusion can be obtained by therelations among a pressure difference between chambers, scatteringprobability, and respective pressures. When a pressure ratio of P2 to P1(P2/P1) is equal to or larger than two, the particles begin to scatterand scattering probability increases in proportion as the pressure ratiorises. In the meantime, the smaller both P1 and P2 are, the moredifficult the particles become to scatter. Further, when both P1 and P2are not greater than approximately 100 mTorr, even though the pressureratio is equal to or larger than two, the particles do not scatter.

The above-mentioned relation between a pressure difference betweenchambers and scattering of particles is not limited to the processingchamber 140 and the load-lock chamber 150, and can be similarly appliedto other chambers having a pressure difference such as the load-lockchamber 150 and the transfer chamber 130.

As described above, when the gate valve is opened at the pressure ratioof 2 or more, a shock wave is generated to propagate into the chamber,whereby the particles are scattered in the chamber. This corresponds toa theory in which a shock wave occurs at the pressure ratio of 2 and themagnitude of the shock wave depends on the pressure ratio. On thecontrary, when the pressure difference between the chambers is less thanabout 100 mTorr, even if the pressure ratio is 2 or more, the particlesare not scattered.

Therefore, in the process of opening to atmosphere in the load-lockchamber 150 in accordance with the present invention, if timings ofopening/closing the purge valve or the acid evacuation valve arecontrolled such that the pressure difference between the load-lockchamber 150 and the transfer chamber 130 is less than about 100 mTorr,the particles can be prevented from being swirled up when the gate valveis opened. Further, even though the pressure difference between theload-lock chamber 150 and the transfer chamber 130 is more than about100 mTorr, if timings of opening/closing the purge valve or the acidevacuation valve are controlled such that the pressure ratio is lessthan two, the particles can be prevented from being swirled up along theshock wave.

Further, in the above embodiment, the present invention is applied to acase where opening/closing timings of the purge valve are controlledwhen the load-lock chamber 150 is opened to the atmosphere, but it isnot limited to the load-lock chamber. That is, controlling ofopening/closing timings of the purge valve in accordance with thepresent invention can be applied to a chamber where pressure control isperformed by introducing thereto a purge gas such as N₂ gas before thegate valve is opened.

Further, the shock wave caused when the gate valve between the chambersis opened can be prevented by providing a shock wave preventingmechanism including Laval nozzle that will be described later.

(Example of Substrate Processing Apparatus Including Shock WavePreventing Mechanism)

Hereinafter, there will be described an example of a substrateprocessing apparatus including a shock wave preventing mechanism withreference to the drawings. FIG. 14 shows a shock wave preventingmechanism provided between the load-lock chamber 150 and the processingchamber 140 in the substrate processing apparatus shown in FIG. 1.

Specifically, the shock wave preventing mechanism shown in FIG. 14 isconfigured as follows. Installed between the load-lock chamber 150 andthe processing chamber 140 is a communication pipe (bypass line) 340which communicates with each of them. Further, disposed in the middle ofthe communication pipe 340 are a control valve 350 for opening orclosing the communication pipe 340 and a shock wave propagationpreventing unit 360 having a throttle. The shock wave propagationpreventing unit 360 is for preventing propagation of a shock waveoccurring when the communication pipe 340 is opened via the controlvalve 350. That is, the throttle included in the shock wave propagationpreventing unit 360 can transform the shock wave into a standing wave toprevent the propagation.

In this case, the control valve 350 of the communication pipe 340 isdisposed close to a chamber having a higher pressure, and the shock wavepropagation preventing unit 360 is provided close to a chamber having alower pressure. Accordingly, the propagation of the shock wave can beefficiently prevented because the shock wave occurs in the chamberhaving a lower pressure. When a corrosive gas such as HCl is used as aprocessing gas, generally, the pressure of the load-lock chamber 150 ismade higher than that of the processing chamber 140 such that thecorrosive gas does not enter the load-lock chamber 150. Thus, in theexample shown in FIG. 14, the control valve 350 of the communicationpipe 340 is disposed close to the load-lock chamber 150 in a line 342 ofthe communication pipe 340, and the shock wave propagation preventingunit 360 is provided close to the processing chamber 140 between lines342 and 344 forming the communication pipe 340.

Something to prevent the propagation of the shock wave, e.g., a nozzlehaving a throttle, is available as the shock wave propagation preventingunit 360. For example, the shock wave propagation preventing unit 360includes a Laval nozzle depicted in FIG. 15. The Laval nozzle has athrottle as shown in FIG. 15 and, specifically, includes a reductionpart 362; a throat part 364; and an extension part 366. Further, asshown in FIG. 16, a shock wave propagation preventing unit 370 may beconfigured as a nozzle having a throttle and extension parts disposed atboth sides of the throttle. In addition, the shock wave propagationpreventing unit 360 is not limited to the above configuration. Forexample, it is possible to prevent the propagation of the shock wave byproviding an orifice or a filter formed of porous ceramic, porous carbonor the like in the communication pipe 340.

In the substrate processing apparatus including the shock wavepropagation preventing unit 360 shown in FIG. 14, the communication pipe340 is opened by the control valve 350 before the gate valve 144. Atthis time, depending on a pressure difference between the processingchamber 140 and the load-lock chamber 150, a shock wave occurs in thecommunication pipe 340. However, the shock wave is transformed into astanding wave in the communication pipe 340 by the shock wavepropagation preventing unit, e.g., the Laval nozzle. Accordingly, theshock wave can be prevented from propagating into the processing chamber140 and particles can be prevented from being swirled up in theprocessing chamber 140.

Further, since the processing chamber 140 and the load-lock chamber 150communicate with each other by opening the communication pipe 340, it ispossible to sufficiently reduce the pressure difference between theprocessing chamber 140 and the load-lock chamber 150. Then, when thepressure difference between the processing chamber 140 and the load-lockchamber 150 is lowered to a value at which a shock wave does not occur,the gate valve 144 is opened. By doing this, even though the gate valve144 is opened, a shock wave does not occur, whereby the particles can bedefinitely prevented from being swirled up along the shock wave.

As described above, by simply providing the communication pipe 340including the shock wave propagation preventing unit 360 between thechambers, even if a shock wave occurs in the communication pipe 340, theshock wave can be transformed into a standing wave. Thus, when thecommunication pipe 340 is opened as well as when the gate valve 144 isopened, the particles can be effectively prevented from being swirled upalong the shock wave. Further, in accordance with the substrateprocessing apparatus shown in FIG. 14, since a shock wave is preventedfrom propagating into the processing chamber 140 that can be easilycontaminated with particles, it is possible to efficiently prevent aparticle contamination to the substrate.

(Modified Example of Substrate Processing Apparatus Including Shock WavePreventing Mechanism)

Hereinafter, there will be described a modified example of a substrateprocessing apparatus including a shock wave preventing mechanism withreference to the drawings. FIG. 17 schematically shows a configurationof the modified example of the substrate processing apparatus includingthe shock wave preventing mechanism. Here, the shock wave preventingmechanism is applied to the substrate processing apparatus using acorrosive gas as a processing gas.

When a corrosive gas is employed as a processing gas in the processingchamber 140, a communication pipe 340 is configured as in FIG. 17 inorder to protect the communication pipe 340 from the corrosive gas. Thatis, the communication pipe 340 is provided with a control valve 430 in aline 344 disposed between a shock wave propagation preventing unit 360and the processing chamber 140 in addition to a control valve 350disposed in a line 342. Further, in the middle of the line 344 of thecommunication pipe 340, a gas evacuation pipe 420 is connected betweenthe shock wave propagation preventing unit 360 and the control valve430. Moreover, the gas evacuation pipe 420 is provided with a controlvalve 440 and connected to a vacuum pump 410 such as a dry pump forevacuating the communication pipe 340 to vacuum.

In the substrate processing apparatus shown in FIG. 17, the followingprocess is performed before the gate valve 144 is opened. First, whenboth of the control valves 350 and 430 are closed in the communicationpipe 340, the communication pipe 340 is evacuated to vacuum by thevacuum pump 410. Accordingly, a processing gas remaining in thecommunication pipe 340 is evacuated. At this time, the pressure of thecommunication pipe 340 is made lower than that of the processing chamber140.

Next, the control valve 430 close to the chamber having a lower pressure(the processing chamber 140 in the example shown in the FIG. 17) isopened. At this time, a shock wave may occur depending on a pressuredifference between the communication pipe 340 and the processing chamber140. However, since the communication pipe 340 previously evacuated tovacuum has a lower pressure than that of the processing chamber 140 anda shock wave occurs in the communication pipe 340, particles areprevented from being swirled up along the shock wave in the processingchamber 140 and the substrate is not contaminated. Further, because thecontrol valve 350 close to the load-lock chamber 150 is closed, theshock wave generated when the control valve 430 is opened does notpropagate into the load-lock chamber 150. Consequently, although thecontrol valve 430 of the communication pipe 340 is opened, particles areprevented from being swirled up along the shock wave in the load-lockchamber 150.

Subsequently, the control valve 350 close to the load-lock chamber 150is opened. At this time, a shock wave may occur in the communicationpipe 340 close to the lock chamber 150 having a lower pressure dependingon a pressure difference between the load-lock chamber 150 and theprocessing chamber 140. However, since the shock wave is transformedinto a standing wave by the shock wave propagation preventing unit, forexample, a Laval nozzle, the shock wave does not propagate into theprocessing chamber 140. Thus, particles are prevented from being swirledup along the shock wave in the processing chamber 140 and the substrateis not contaminated.

Further, since the magnitude of the shock wave is proportional to thepressure ratio of the chambers, it is preferable that the process isperformed after respective pressures of the chambers are adjusted suchthat the pressure ratio of the chambers is not excessively high.

Further, the vacuum processing of the communication pipe 340 may beperformed simultaneously when the processing chamber 140 is vacuumprocessed after the substrate is unloaded from the processing chamber140 and the gate valve 144 is closed. In other words, if the controlvalve 430 close to the processing chamber 140 is opened while theprocessing chamber 140 is vacuum processed, the communication pipe 340as well as the processing chamber 140 can be vacuum processed by thesame vacuum pump for vacuum processing the processing chamber 140.Accordingly, it is also possible to eliminate the gas evacuation pipe420 or the vacuum pump 410 for vacuum processing the communication pipe340.

Moreover, in the examples shown in FIGS. 14 and 17, although the shockwave preventing mechanism is provided between the chambers having apressure difference, i.e., the processing chamber 140 and the load-lockchamber 150, the present invention is not limited thereto, and the shockwave preventing mechanism may be provided between various types ofchambers. For example, the shock wave preventing mechanism can bedisposed between the load-lock chamber 150 and the transfer chamber 130.

(Substrate Processing Apparatus in Accordance with Another Embodiment)

Hereinafter, there will be described a substrate processing apparatus inaccordance with another embodiment of the present invention. Forexample, the present invention is not limited to the substrateprocessing apparatus shown in FIG. 1, and can be applied to varioustypes of substrate processing apparatuses. FIG. 18 shows a schematicconfiguration of a substrate processing apparatus including a vacuumprocessing unit formed of multiple chambers.

The substrate processing apparatus 500 shown in FIG. 18 includes avacuum processing unit 510 having multiple processing chambers 540 forperforming various kinds of processes such as a film-forming process andan etching process on a substrate to be processed, e.g., semiconductorwafer W; and a transfer unit 120 for loading/unloading the wafer Winto/from the vacuum processing unit 510. Because the transfer unit 120has a same configuration as the one shown in FIG. 1, like referencenumerals will be given to like parts and, further, a redundantdescription will be omitted. The transfer unit 120 shown in FIG. 18includes a common transfer mechanism (atmospheric side transfermechanism) 160 in a transfer chamber 130, and the common transfermechanism 160 is configured as a single arm mechanism having one pick. Abase 162 on which the common transfer mechanism 160 is fixed is slidablysupported on a guide rail 164 disposed in a central portion of thetransfer chamber 130 in a longitudinal direction thereof. Each of thebase 162 and the guide rail 164 has a mover and a stator for a linearmotor. A linear motor driving mechanism 166 for driving the linear motoris disposed at an end of the guide rail 164. The linear motor drivingmechanism 166 is connected to a controller 180. Accordingly, based oncontrol signals from the controller 180, the linear motor drivingmechanism 166 is operated and the common transfer mechanism 160 and thebase 162 move along the guide rail 164 in an arrow direction.

FIG. 18 shows the vacuum processing unit 510 having, e.g., sixprocessing chambers 540A, 540B, 540C, 540D, 540E and 540F, wherein thevacuum processing unit 510 is disposed on the side of the transfer unit120. The vacuum processing unit 510 includes a common transfer chamber550 for loading/unloading the wafer W into/from the six processingchambers 540A to 540F. Further, the processing chambers 540A to 540F arearranged around the common transfer chamber 550 via gate valves 544A,544B, 544C, 544D, 544E and 544F, respectively. Further, a first and asecond load-lock chamber 560M and 560N capable of being vacuum processedare connected to the common transfer chamber 550 via gate valves 554Mand 554N, respectively. Furthermore, the first and the second load-lockchamber 560M and 560N connected to the side of the transfer chamber 130via the gate valves 562M and 562N, respectively.

In the aforementioned cluster tool type processing apparatus, the gatevalves can be opened or closed airtightly between the common transferchamber 550 and the six processing chambers 540A to 540F and between thecommon transfer chamber 550 and the load-lock chambers 560M and 560N tothereby communicate with each other when necessary. Further, the gatevalves can be opened or closed airtightly between the transfer chamber130 and the first and the second load-lock chamber 560M and 560N.

In the processing chambers 540A to 540F, a same process or differentprocesses may be performed on the wafer W. Susceptors 542A, 542B, 542C,542D, 542E and 542F for mounting thereon the wafer W are disposed in theprocessing chambers 540A to 540F, respectively. Further, the number ofthe processing chambers 540 is not limited to six and may be seven ormore.

A pressure control is performed in the load-lock chambers 560M and 560Nwhile the wafer W is temporarily supported therein and, then, theprocess moves onto the next step. The load-lock chambers 560M and 560Nmay be configured to also have a cooling mechanism or a heatingmechanism. Further, gas piping of each of the load-lock chambers 560Mand 560N is configured same as that shown in the FIG. 2.

A transfer mechanism (vacuum side transfer mechanism) 570 formed of, forexample, a multi-joint arm capable of stretching, bending, elevating andrevolving is disposed in the common transfer chamber 550. The transfermechanism 570 is rotatably supported on a base 572. The base 572 isslidably supported on a guide rail 574, which is disposed from the frontside to the back side in the common transfer chamber 550, for example,by an arm mechanism 576. Thus, it is possible to access the load-lockchambers 560M and 569N and the processing chambers 540A to 540F bysliding the transfer mechanism 570 along the guide rail 574. Forexample, when accessing the load-lock chambers 560M and 560N and theprocessing chambers 540A and 540F, the transfer mechanism 570 is movedalong the guide rail 574 and positioned at the back side of the commontransfer chamber 550. Further, when accessing the four processingchambers 540B to 540E, the transfer mechanism 570 is moved along theguide rail 574 and positioned at the front side of the common transferchamber 550. Accordingly, it is possible to access all chambersconnected to the common transfer chamber 550, i.e., the load-lockchambers 560M and 560N, and the processing chambers 540A to 540F, byonly using the transfer mechanism 570. The transfer mechanism 570 hastwo picks so as to handle two wafers at the same time.

Further, the transfer mechanism 570 is not limited to the aboveconfiguration, and two transfer mechanisms may be provided. For example,a first and a second transfer mechanism, each having a multi-joint armcapable of stretching, bending, elevating and revolving, may be disposedat the back side and the front side in the common transfer chamber 550,respectively. Moreover, the number of the picks of the transfermechanism 570 is not limited to two, and the transfer mechanism 570 mayhave just one pick.

When the gate valve 562M (562N) is opened between the transfer chamber130 of the transfer unit 120 and the load-lock chamber 560M (560N) inthe substrate processing apparatus 500 shown in FIG. 18, a process ofopening to atmosphere is performed by introducing the purge gas into theload-lock chamber 560M (560N) in a same way as that in the substrateprocessing apparatus shown in FIG. 1. Thus, the process of opening toatmosphere shown in FIG. 5 or 9 in accordance with the presentinvention, wherein timings of closing the control valve (purge valve) V1and opening the acid evacuation valve V8 can be freely set, can beapplied to the process of opening to atmosphere in the load-lock chamber560M (560N).

Therefore, it is prevented that the pressure of the load-lock chamber560M (560N) becomes needlessly increased, thereby preventing particlesfrom being swirled up in the load-lock chamber 560M (560N). Further, theprocessing gas such as corrosive gas remaining in the load-lock chamber560M (560N) can be evacuated in advance before the gate valve 562M(562N) is opened.

Further, when one of the gate valves 544A to 544F is opened between thecommon transfer chamber 550 and a corresponding one of the processingchambers 540A to 540F, the purge gas is introduced into the commontransfer chamber 550 in order to prevent the processing gas such ascorrosive gas from flowing into the common transfer chamber 550 from thecorresponding one of the processing chambers 540A to 540F. Thus, thepressure of the common transfer chamber 550 is usually made higher thanthat of each of the processing chambers 540A to 540F. Since there existsa pressure difference between the common transfer chamber 550 and eachof the processing chambers 540A to 540F, a shock wave can be generateddepending on the pressure difference to make particles be swirled up.Therefore, a shock wave preventing mechanism similar to the one shown inFIG. 14 or 17 is provided between the common transfer chamber 550 andeach of the processing chambers 540A to 540F, whereby particles arecertainly prevented from being swirled up as in the substrate processingapparatus 100 shown in FIG. 1.

(Self-Check Process of Chamber)

In respective chambers, for example, the processing chambers 140 and 540and the load-lock chambers 150 and 560 shown in FIGS. 1 and 18, aself-check process may be performed for the purpose of improvingoperating efficiency for regular maintenance and shortening operatingtime. In the self-check process, a vacuum system for performing a vacuumprocessing (evacuating) by using a vacuum pump and a gas system forsupplying a specified gas such as processing gas or purge gas arechecked.

Such a self-check process will be described in detail with reference tothe drawings. FIG. 19 is a flowchart showing a general example of theself-check process in the processing chambers 140 and 540. First, avacuum processing is performed by the vacuum system at step S810. For avacuum evacuation valve is opened and the processing chambers 140 and540 are vacuum processed by operating the vacuum pump. Then, at stepS820, it waits until a mass flow controller (MFC) that is disposed in,e.g., a processing gas introduction pipe of the gas system isstabilized.

Then, if it is determined that the MFC stability waiting time haselapsed at step S820, the process proceeds to step S830 where aspecified gas (e.g., processing gas in the self-check process of theprocessing chamber 140 or 540) is introduced and while a pressure ismonitored by a diaphragm vacuum gauge, e.g., a capacitance manometer,disposed in the processing chamber 140 or 540, the pressure is raised upto a predetermined value (build up). As described above, when theprocessing gas is introduced, the pressure is monitored by the diaphragmvacuum gauge capable of extensively measuring the pressure. Thediaphragm vacuum gauge employing a thin metal film can measure pressuresranging from 10⁻⁴ Torr to 10² Torr by detecting a change in aelectrostatic capacitance. In the diaphragm vacuum gauge, for example,an inner space of its container is divided into two portions by the thinmetal film, wherein one portion is sealed to vacuum and the otherportion communicates with the processing chamber.

Subsequently, at step S840, while the pressure is monitored by a vacuumgauge employing a measuring device disposed in a vacuum evacuation pipe,e.g., a Convectron gauge, a vacuum processing is performed. Here, sincethe vacuum processing is performed, the pressure is measured by thevacuum gauge disposed in a vacuum evacuation pipe. As the vacuum gaugeemploying a measuring device, there are a Pirani vacuum gauge, a quartzfriction vacuum gauge and the like in addition to the above-mentionedConvectron vacuum gauge. The Convectron vacuum gauge or Pirani vacuumgauge can measure pressures generally ranging from 10⁻³ Torr to 1 Torrby detecting a temperature change in the measuring device formed of fineplatinum lines, i.e., a change in an electric resistance. Further, thequartz friction vacuum gauge can measure pressures generally rangingfrom 10⁻² Torr to 10³ Torr by detecting a variation in a resonance stateof a tuning fork shaped quartz oscillator. As the quartz friction vacuumgauge, for example, there is a crystal gauge that is a hybrid vacuumgauge combining the quartz friction vacuum gauge with a B-A typeionization vacuum gauge. The vacuum gauge employing the measuring devicefeatures that the pressure is measured by exposing the measuring deviceto gas.

Next, sequential steps S850, S860 and S870 are executed similarly to theway steps S820, S830 and S840 are executed and a whole self-checkprocess is finished.

As described above, in the self-check process shown in FIG. 19, thepressure is monitored by using the diaphragm vacuum gauge when theprocessing gas is introduced (build up) at steps S830 and S860, whereasthe pressure is monitored by a vacuum gauge employing a measuring devicedisposed in a vacuum evacuation pipe when vacuum processing at stepsS840 and S870.

The vacuum gauge employing the measuring device measures the pressure bydirectly exposing the measuring device to the processing gas flowing inthe vacuum evacuation pipe unlike the diaphragm vacuum gauge. Thus, thelonger time the measuring device is exposed to the processing gas, thehigher the probability for the malfunction or wearing down in the vacuumgauge employing the measuring device becomes compared to the diaphragmvacuum gauge. Accordingly, as shown in FIG. 19, if the vacuum gaugeemploying the measuring device is used even for the self-check processdifferent in addition to an actual substrate processing, the vacuumgauge may break down more frequently, thereby shortening its life span.

Further, a pressure range where the vacuum gauge employing the measuringdevice can measure pressure is included in a pressure range where thediaphragm vacuum gauge can measure pressure. Specifically, the vacuumgauge employing the measuring device such as the Convectron vacuum gaugeor Pirani vacuum gauge can measure pressure ranging from 10⁻³ Torr to 1Torr, and the quartz friction vacuum gauge can measure pressure rangingfrom 10⁻² Torr to 10³ Torr. Thus, a measurement range of those gauges isincluded in a measurement range, 10⁻⁴ Torr to 10³ Torr, of the diaphragmvacuum gauge such as a capacitance manometer. Accordingly, the diaphragmvacuum gauge can be used instead of the vacuum gauge employing themeasuring device.

Therefore, in the self-check process, the diaphragm vacuum gauge such asthe capacitance manometer is used instead of the vacuum gauge employingthe measuring device, whereby the malfunction or wearing down isprevented from occurring in the vacuum gauge employing the measuringdevice.

FIG. 20 shows an example of the self-check process in which the vacuumgauge employing the measuring device is not used. First, a vacuumprocessing is performed by the vacuum system at step S910. Then, at stepS920, it waits until a mass flow controller (MFC) that is disposed in,e.g., a processing gas introduction pipe of the gas system isstabilized. Then, if it is determined that the MFC stability waitingtime has elapsed at step S920, the process proceeds to step S930 where aspecified gas (e.g., processing gas in the self-check process of theprocessing chamber 140 or 540) is introduced and while a pressure ismonitored by a diaphragm vacuum gauge, e.g., a capacitance manometer,disposed in the processing chamber 140 or 540, the pressure is raised upto a predetermined value (build up). Steps S910˜S930 are executedsimilarly to steps S810˜S830 shown in FIG. 19.

Subsequently, at step S940, while the pressure is monitored by thediaphragm vacuum gauge (e.g., a capacitance manometer), a vacuumprocessing is performed by the vacuum system. At this time, when thereis provided the vacuum gauge employing a measuring device (e.g., aConvectron vacuum gauge, a Pirani vacuum gauge, a quartz friction vacuumgauge), its protection valve is closed to prevent the processing gassuch as corrosive gas from entering the vacuum system.

Next, sequential steps S950, S960 and 5970 are executed similarly tosteps S920, S930 and S940 and a whole self-check process is finished.

As described above, in the self-check process shown in FIG. 20, thepressure is monitored by using the diaphragm vacuum gauge (e.g., acapacitance manometer) when vacuum processing at steps S940 and S970 aswell as when the processing gas is introduced (build up) at steps S930and S960. As described above, the self-check process is performedwithout using the vacuum gauge employing a measuring device (e.g.,Convectron vacuum gauge, Pirani vacuum gauge, a quartz friction vacuumgauge) to thereby reduce the probability for malfunction of the vacuumgauge employing a measuring device and extend its life span.

While the invention has been shown and described with respect to thepreferred embodiments, it will be understood by those skilled in the artthat various changes and modifications may be without departing from thespirit and scope of the invention as defined in the following claims.

1. A substrate processing apparatus, comprising: a transfer unit fortransferring a substrate to be processed between chambers accommodatingtherein the substrate; at least one vacuum processing unit connected tothe transfer unit and including at least one vacuum preparation chamberand at least one vacuum processing chamber, wherein said at least onevacuum preparation chamber is connected to the transfer unit via a gatevalve and has a nonreactive gas introducing unit, a corrosive gasevacuation unit and an opening-to-atmosphere unit, and wherein said atleast one vacuum processing chamber is configured to perform a processon the substrate loaded therein via the vacuum preparation chamber byusing a corrosive gas as a processing gas; and a controller configuredto: introduce a nonreactive gas into the vacuum preparation chamber bycontrolling a gas introduction valve of the nonreactive gas introducingunit before the gate valve is opened for substrate transfer between thevacuum preparation chamber of the vacuum processing unit and thetransfer unit; stop introducing the nonreactive gas by controlling thegas introduction valve of the nonreactive gas introducing unit when thecontroller determines that an inner pressure of the vacuum preparationchamber becomes equal to an atmospheric pressure, start an evacuationprocess of a corrosive gas in the vacuum preparation chamber bycontrolling an evacuation valve of the corrosive gas evacuation unit andthen open to atmosphere performed by letting the vacuum preparationchamber communicate with an atmosphere by controlling anopening-to-atmosphere valve of the opening-to-atmosphere unit; and openthe gate valve after the step of opening to atmosphere.
 2. The substrateprocessing apparatus of claim 1, wherein timings of stopping introducingthe nonreactive gas and starting the evacuation process of the corrosivegas are freely set by the controller.
 3. The substrate processingapparatus of claim 2, wherein timings of stopping introducing thenonreactive gas and starting the evacuation process of the corrosive gasare equal to a timing when the inner pressure of the vacuum preparationchamber becomes same as the atmospheric pressure by the controller. 4.The substrate processing apparatus of claim 1, wherein the corrosive gasevacuation unit includes a backflow detecting unit for detecting abackflow in the evacuation process, and when the backflow is detected inthe evacuation process by the backflow detecting unit after opening theevacuation valve of the corrosive gas evacuation unit, the controllerperforms an error process if the backflow is not controlled within aspecified time period and the controller does not perform the errorprocess if the backflow is controlled within a specified time period. 5.The substrate processing apparatus of claim 1, wherein a shock wavepreventing mechanism for preventing a shock wave occurring depending ona pressure difference between the vacuum preparation chamber and thetransfer unit is provided therebetween.
 6. The substrate processingapparatus of claim 5, wherein the shock wave preventing mechanismincludes: a communication pipe for letting the vacuum preparationchamber communicate with the transfer unit or the vacuum processingchamber; a shock wave propagation preventing unit disposed in thecommunication pipe; and a communication pipe opening/closing valvedisposed at one side of the shock wave propagation preventing unit,close to the vacuum preparation chamber having a higher pressure.
 7. Thesubstrate processing apparatus of claim 1, wherein a shock wavepreventing mechanism for preventing a shock wave occurring depending ona pressure difference between the vacuum preparation chamber and thevacuum processing chamber is provided therebetween.